Cathode ray tube



Sepit. 8K, 1936. M. DAVIS CATHODE RAY TUBE Original Filed Jan. 26, 1953 Patented Sept. 8, 1936 CATHODE RAY TUBE Merlin Davis, Milton, Pa.

Original application January 26, 1933, Serial No.

653,684. Divided and this application November 28, 1933, Serial No. 700,107

7 Claims.

(Cl. Z50-27.5)

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by' or for the GovernmentI of the United States for governmental purposes only without the payment of any royalty thereon.

My invention relates to the (electrical) production of complex electrical impulse useful for the production of sound in 'a musical instrument, as a harmonic synthesizer, or in other detecting or m indicating instruments.

application Serial No. 653,684, filed January 26, 1933.

An object of my invention is a novel and improved method and means for the production or generation of electrical impulses, which may subsequently be transferred into sound or other forms of energy.

Another object of the present invention is the provision of an instrumentality of the cathode tube type, which, when incorporated in a suitable electrical system, such as described in my copending application above mentioned as one example, will produce simultaneously a number of alternating currents of different frequencies which may be varied in their amplitudes without changing the original frequency ratios. Still another object of the present invention is the provision of an instrumentality of the cathode tube type for producing an electrical impulse of complex wave form and variable frequency, in which the sinusoidal elements, of which it is composed, may be independently controlled.

The advantage of this type of instrument for 5 generating complex electrical impulses is that it provides compact, comparatively simple and inexpensive physical means whereby the frequency impulses obtainable are not limited such as they may be in devices having mechanical moving 4() `lparts, and also the time required to change from one frequency to another is not limited as in devices having moving mechanical elements wherein the inertia is a limiting factor.

The accompanying drawing illustrates several examples of means for carrying out the invention,

of which:-

Figure 1 is a longitudinal cross section of one form of my invention,

Figure 2 is a longitudinal cross section of Figure 1,

Figure 3 is a detail of a portion of one element of my tube,

Figure 4 is a longitudinal cross section of a modified form of my invention, and

Figure 5 is a longitudinal cross section of the latter form corresponding to Figure 2.

This application is a division of my copending Broadly the invention resides in a moving electron beam which is intercepted by one or more receptors limited in the shape of their effective areas such as to provide an electrical charge upon receptor which will vary progressively in proportion to its shape. As an example of means for carrying out the invention I employ a cathode tube generally of the type found in a cathode ray oscillograph, but modified to lend itself for the purposes of the invention. 10

Referring to Figure 1 of the drawing, I denotes generally a partially evacuated tube having at one end an oxide coated filament 2 which may be surrounded by a cylinder 3 at a negative potential from a lead 23 for concentrating the electrons 15 given off by the heated lament and for minimizing positive bombardment. The metallic partition 4 has a potential impressed upon it from a lead 24 and accelerates toward it the electrons which have been generated by the heated illament. The partition 4 has a small opening 5 therein opposite the filament and some of the electrons pass through the opening in this plate and constitute the cathode beam, C, shown in dotted lines, which will take the form of a pencil of rays. These pass between two sets of parallel 25 opposite plates 6 and 1 upon which are impressed alternating charges through conductors 26 and 21 respectively.

Under these conditions the set of deflection plates 6 have a tendency to swingingly oscillate 30 the beam in one plane between the plates while the plates l tend to oscillate the beam in a plane at substantially right angles to plane of oscillation caused by the plates 6, as shown in dotted lines in Figures 1 and 2. n 35 The deflection plates 6 may have impressed upon them a voltage which varies at a rather low frequency while a much higher frequency is used with the vertical deecting plates l, the latter, as shall be seen later, constituting a manner of introducing a carrier wave.

In the other end portion of this tube, there is a plurality of metallic receptor plates 8 upon which the electron beam impinges and which conduct the charges as received to a plurality of suitable external circuits I6. The plurality of openings i0 and i0-a., as well as the receptor plates 8 and 8-a are arranged in straight line formation so as to be swept by the swinging oscillating beam, as

- will be clearly seen from an inspection of Figs. 1, 5

2, and 4. Because of the simultaneous alternating voltages on the deflection plates` the impinging spot of electrons from the cathode beam scans the reception plates always in one direction, but at 55 the same time progressing back and forth in the other direction/at substantially right angles to said ilrst direction.

If now a metallic plate 9 containing a plurality of openings i of the required shape is placed close to but between the receptor plates 8 and the deection plates 8 and I and if this plate is kept at a constant potential somewhat below that of the receptor plates 8, then the number of openings opposite a given receptor plate should govern the frequency of the impulses on that plate `at a given beam sweep frequency as governed by deection plates 8 and the proper combination of sweep speed in the direction controlled by plate 6 and the shape of opening will determine the electrical wave form discharging from the receptor plates through their conductors I6.

If a sine wave form is desired and the sweep speed governed by plates is constant velocity, both Y.

in its forward and return stroke, or if, the swe'ei's' of one velocity in one direction and of another in the return direction or stroke, as occurs in the relaxation type of oscillators, the shape of the openings in both instances may be of the form as is more clearly shown in Figure 3. Here in case of producing musical sounds a fundamental is followed by two, three, four, etc.. times the number of openings corresponding to the number of openings for the fundamental to produce harmonics. If the sweep were not uniform of velocity in both directions, the openings may be made to compensate for the lack of uniformity of the sweep. (This has been described and illustrated in patent application Serial No. 653,684, Fig. 17 and description thereof.)

Figures 4 and 5 illustrate a form of tube where no carrier wave is introduced in the tube. In this case the plates 1, shown in Figures 1 and 2, are omitted. Also the oxide lament in this case, extends the width of the tube to obtain a flat or ribbon-like cathode beam C'. The cylinder 3 is replaced by a pair of plates I2 having a negative potential impressed thereupon by lead I2 while the positive plate d'has an elongated narrow slit I3 therein, in lieu of a small hole 5 in the plate I shown in Figures 1 and 2, so that a narrow ribbon of rays, in place of a pencil of electrons, issues from this opening I3.

In this case, the parallel deection plates 6' cause the ribbon of cathode rays to sweep back and forth across the elements 8a and 9*, which may be the same as employed in Figures 1 and 2, when an oscillator is connected to the deflection plates 6B. It is to be noted that these must also be elongatedto deect the full length of the ribbon of cathode ray, C'. In this form of the invention the scanning effect of pencil-like beam C produced by the deection plates 1, in Figures 1 and 2 is made unnecessary.

Although the cathode tube has been illustrated as that of the hot cathode type, it is understood that a cold cathode type might also be used.

Also, other changes, variations and modiiications may be made, and the invention is only to be limited by the scope of the claims.

Having thus described the invention, what is claimed is:

1. A cathode ray tube comprising an accelerating anode provided with an elongated slit, a cathode having an element parallel with said elongated slit, a single set of deecting plates parallel with and of substantially the width of a beam passing through said elongated slit, an absorbing screen provided with a plurality of openings of predetermined shapes to control the shape of the beam passing therethrough, and a plurality of receptor plates mounted adjacent to said absorbing screen`for intercepting substantially all of the electrons passing through the said screen openings.

2. A cathode ray tube for supplying a plurality of fluctuating currents to a plurality of circuits which includes an accelerating anode, a set of parallel defiecting plates, a cathode having an element parallel with said plates, an absorbing screen provided with a plurality of openings oi' predetermined varying shapes for producing electrical impulses of desired wave forms, and a plurality of receptor plates for intercepting substantially all of the electrons passing through the said screen openings.

3. A cathode ray tube for supplying a plurality oi nuctuating currents toa-plurality of conductors, which Vcomprises means for supplying an oscillating cathode ray to one or more receptor plates, means for intercepting upon said receptor plates substantially all of the electrons falling upon areas of predetermined shapes, and means for intercepting substantially all of the electrons not intercepted by said plates.

4. A cathode ray tube comprising an accelerating anode provided cathode having an element parallel with said elongated slit, a single set of deiiecting plates parallel with and of substantially the width of a beam passing through said slit, an absorbing screen provided with a, plurality of openings of predetermined shapes, and adapted to be maintained at a constant potential and a plurality of receptor plates mounted adjacent to said absorbing screen for intercepting substantially all of the electrons passing through the said screen openings.

5. A cathode ray tube for supplying a plurality of nuctuating currents to a plurality of conductors, which includes an oscillating anode, two sets of opposing parallel deiiecting plates adapted to having impressed thereon alternating electrical charges, each set of plates being substantially at right angles to the plates of the other set, an absorbing screen provided with a plurality of independent openings of predetermined shapes arwith an elongated slit, a

ranged in straight-line formation, cathodev anode l elements in association with the said deecting plates in said tube capable of producing a swingmg oscillating beam to successively pass through the independent aligned openings in the absorblng screen, a plurality of independent receptor plates arranged in straight-line formation with respect to the openings in the absorbing screen for intercepting substantially all of the electrons passing through the said openings in the absorbing screen and electrical conductors connected to said receptor plates.

6. A cathode ray tube of the character described, including a lament adapted to be heated, means for concentrating the electrons given' oft by the heated iilament and for minimizing the positive bombardment, means associated with the filament for accelerating the electrons and being such as to permit the electrons o1' the cathode beam to pass therefrom, means for swmgmgly oscillating said beam, a receptor means for receiving the electrons of the beam thereon, means for intercepting the beam, said means having separate openings arranged in straight-line formation, the areas of the openings being of differently defined shapes to permit the swinging oscillating beam to successively pass through said openings to said receptor means aosanos and electrical conductors connected to said receptor means.

7. A cathode ray tube of the character described including a filament adapted to be heated, means for concentrating the electrons given oi by the heated filament and for minimizing the positive bombardment, means associated with the iilament for accelerating the electrons and being such as to permit the electrons of the cathode beam to pass therefrom, means for swingingly oscillating said beam, absorbing means having separate openings of diiierently denned shapes arranged in straight-line formation, receptor means for receiving the electrons of the beam which pass through the differently shaped openings in the absorbing means, said absorbing means intercepting the rays of the beam which do not pass through the said openings to the receptor means, the shapes of the areas on the receptor means which receive the electrons of the beam being dened by the shapes of the openings in the absorbing means, and electrical l0 conductors connected to said receptor means.

- MERLIN DAVIS. 

